Onlooker Rodrigo Barrera captured this time-lapse of the eruption Wednesday evening as the sun set on the plume, then shared the spectacular 22-second video on YouTube.
As of Thursday morning, upwards of 4,000 people have been evacuated from around the base of the volcano. Chilean authorities told Reuters Wednesday the largest threat from the eruption is of possible pyroclastic flows, mixtures of burning rock and gas that can travel down from the volcano at speeds as high as 185 mph.
"In this situation, with the eruption column so high, the main risk is that it collapses, falls due to gravity because of its own weight and causes a pyroclastic flow," said Gabriel Orozco, a vulcanologist with Chile's National Geology and Mining Service.
View photos of the eruption here.